Modern positioning technologies are based on generating large databases containing information on radio nodes, e.g. Wireless Local Area Network (WLAN) access points (APs), and their signals. The information may for instance originate at least partially from users of these positioning technologies acting as voluntary data collectors.
The observation data provided by the data collector terminals, for instance mobile terminals, is typically in the form of “fingerprints”, which contain a position information, e.g. determined based on a map and/or obtained based on received satellite signals of a global navigation satellite system (GNSS) or another positioning system, radio node identification information identifying the one or more radio nodes that are observed by the data collector terminal, and radio measurement values, i.e. measurements of radio parameters pertaining to the observed radio nodes such as for instance a Received Signal Strength (RSS).
This observation data may then be transferred to a server or cloud, where the data (usually of a multitude of data collectors) may be collected and where radiomaps for positioning purposes may be generated and/or updated based on the collected data.
In the end, these radiomaps may be used for estimating a position, e.g. the position of a mobile terminal. This may function in two modes. The first mode is the terminal-assisted mode, in which the mobile terminal performs the radio measurements with respect to observed radio nodes to obtain radio measurement values via an air interface, and provides the identifiers of the observed radio nodes and the radio measurement values as observation data to a remote server, which in turn, based on the radiomaps, determines and provides the position estimate back to the mobile terminal. The second mode is the terminal-based mode, in which the mobile terminal has a local copy of the radiomaps (or only a subset thereof, as currently required by the mobile terminal), e.g. downloaded by the mobile terminal from a remote server or pre-installed in the mobile terminal, and performs the positioning itself (i.e. locally).